Coherent Control of Evanescent Waves via Beam Shaping

TL;DR

This paper demonstrates that the transmittance of evanescent waves in FTIR can be coherently controlled by shaping the incident beam, combining experimental and simulation results to show potential for advanced applications.

Contribution

It introduces a novel method of controlling evanescent wave transmittance through beam shaping in FTIR using interferometric techniques.

Findings

Transmittance varies with beam path length difference.

Results from experiment and simulation are in agreement.

Beam shaping can be used to control evanescent wave transmittance.

Abstract

Evanescent waves are central to many technologies such as near-field imaging that beats the diffraction limit and plasmonic devices. Frustrated total internal reflection (FTIR) is an experimental method commonly used to study evanescent waves. In this paper, we shape the incident beam of the FTIR process with a Mach-Zehnder interferometer and measure light transmittance while varying the path length difference and interferometric visibility. Our results show that the transmittance varies with the path length difference and, thus, the intensity distribution of the shaped beam. Experiment and finite element method simulation produce results that agree. We also show, through simulations, that the transmittance can be controlled via other methods of beam shaping. Our work provides a proof-of-concept demonstration of the coherent control of the FTIR process, which could lead to advancements in numerous applications of evanescent waves and FTIR.